Operator Balance Chart
A graphic tool that assists the creation of continuous flow in a multistep, multioperator process by distributing operator work elements in relation to takt time. (Also called an operator loading diagram or a yamazumi board.)
An OBC (shown on the next page) uses vertical bars to represent the total amount of work each operator must do compared to takt time. The vertical bar for each operator is built by stacking small bars representing individual work elements, with the height of each element proportional to the amount of time required. Creating an operator balance chart helps with the critical task of redistributing work elements among operators. This is essential for minimizing the number of operators needed by making the amount of work for each operator very nearly equal to, but slightly less than, takt time.